Draw path on google map based on lat lang

Question

i want to draw path on google map.

Basically what i am tracking user locaion after specfic time interval. when user reach to some destination then i need to draw the path which he followed to reach that destination.

It is working fine but the problem is it is showing zigzag path. See the image below.

What i want:

I want to draw a proper path followed by the points that i get during tracking.

What i have tried

i searched and found this link in which we can pass up to 8 points to get the directions. Which is the maximum limit allowed to the non-business users of the Google Map. Is there any other way to achieve this. because i have so many points to draw on map.

code for drawing polylines

private void drawPath() {
        if (mMap != null)
            mMap.clear();
        int count = 0;
        LatLng prev = null;
        String[] mProjection = {LocTable.COLUMN_ID, LocTable.COLUMN_LONGITUDE, LocTable.COLUMN_LATITUDE};
        String mSelectionClause = LocTable.COLUMN_ID + "> ?";
        String[] mSelectionArgs = {"0"};
        String mSortOrder = LocTable.COLUMN_ID;

        Cursor mCursor = getContentResolver().query(
                LocContentProvider.CONTENT_URI,   // The content URI of the words table
                mProjection,                        // The columns to return for each row
                mSelectionClause,                    // Selection criteria
                mSelectionArgs,                     // Selection criteria
                mSortOrder); 


        if(mCursor != null && mCursor.getCount()!=0) {

            Log.i("cursor", "Count: " + mCursor.getCount() + "|Column count: " + mCursor.getColumnCount());
            if (mCursor.moveToFirst()) {
                do {
                    if (mMap != null) {

                        float lon = mCursor.getFloat(1);
                        float lat = mCursor.getFloat(2);
                        LatLng current = new LatLng(lat, lon);

                        markerPoints.add(current);
                        if (count == 0){
                            prev = current;
                        }
                        CameraUpdate cameraUpdate = CameraUpdateFactory.newLatLngZoom(current, 19);
                        mMap.animateCamera(cameraUpdate);
                        mMap.addPolyline((new PolylineOptions())
                                .add(prev, current).width(6).color(Color.BLUE)
                                .visible(true));
                        prev=current;
                        count++;
                    }
                } while (mCursor.moveToNext());
            }

            mCursor.close();
        }
    }

thanks for help.

Answer 1

I'm agree with antonio's answer. Problem is not with you drawing function. You just drawing path whatever device giving you location. Problem is your device is not giving accurate location.

Let me giving you brief description about Location Functionality.

There are three kind of provider giving location in device.

1 GPS Provider.

This provider determines location using satellites. Depending on conditions, this provider may take a while to return a location fix. Requires the permission ACCESS_FINE_LOCATION.

The extras Bundle for the GPS location provider can contain the following key/value pairs:

satellites - the number of satellites used to derive the fix

2 Network Provider.

This provider determines location based on availability of cell tower and WiFi access points. Results are retrieved by means of a network lookup.

3 Passive Provider.

This provider can be used to passively receive location updates when other applications or services request them without actually requesting the locations yourself. This provider will return locations generated by other providers. You can query the getProvider() method to determine the origin of the location update. Requires the permission ACCESS_FINE_LOCATION, although if the GPS is not enabled this provider might only return coarse fixes.

Reference:

Android Location Manager

Android Location Providers - GPS or Network Provider?

As per my experience I can say GPS Provider is giving you accurate location compare to Network Provider but need open environment, GPS provider is not giving accurate location in inside building.

getAccuracy().

Returns a constant describing horizontal accuracy of this provider. If the provider returns finer grain or exact location, ACCURACY_FINE is returned, otherwise if the location is only approximate then ACCURACY_COARSE is returned.

This method will return exact value when location is changed from GPS Provider otherwise it will return approximate or 0 value.

Ref : Location.getAccuracy()

Solution:

1. Use only GPS Provider

2. Find out your location is accurate or not.

Recommended Use Google Client Sample Example.

Answer 2

The problem is not on your drawing function but on the method you are using to get the points of your path using the received location.

You need to take into account two factors:

• First of all, the accuracy of the received location. You can get the accuracy using the Location.getAccuracy() method (documentation). The accuracy is measured in meters, so the lower the better.
• On the other hand, you may want to add a new location to your polyline only if your new location is farther than a given distance to your last added location.

An example combining both considerations:

private static final float MINIMUM_ACCURACY = 10; // If the accuracy of the measurement is worse than 10 meters, we will not take the location into account
private static final float MINIMUM_DISTANCE_BETWEEN_POINTS = 20; // If the user hasn't moved at least 20 meters, we will not take the location into account
private Location lastLocationloc;

// ...

public void onLocationChanged(Location mylocation) {
    if (mylocation.getAccuracy() < MINIMUM_ACCURACY) {
        if (lastLocationloc == null || lastLocationloc.distanceTo(mylocation) > MINIMUM_DISTANCE_BETWEEN_POINTS) {
            // Add the new location to your polyline

            lastLocationloc = mylocation;
        }
    }
}

Answer 3

Have you looked into the new Roads Api? It will calculate the accuracy and returns the most reasonable values to draw the line from. It also provides the speed limit on the current road.